Patchwork [3/7] extensions: add IPv6 SNAT extension

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Submitter Patrick McHardy
Date Aug. 9, 2012, 8:11 p.m.
Message ID <1344543073-11660-4-git-send-email-kaber@trash.net>
Download mbox | patch
Permalink /patch/176268/
State Superseded
Headers show

Comments

Patrick McHardy - Aug. 9, 2012, 8:11 p.m.
From: Patrick McHardy <kaber@trash.net>

Signed-off-by: Patrick McHardy <kaber@trash.net>
---
 extensions/libip6t_SNAT.c |  247 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 247 insertions(+), 0 deletions(-)
 create mode 100644 extensions/libip6t_SNAT.c
Jan Engelhardt - Aug. 9, 2012, 9:28 p.m.
On Thursday 2012-08-09 22:11, kaber@trash.net wrote:
>+
>+static const struct xt_option_entry SNAT_opts[] = {
>+	{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
>+	 .flags = XTOPT_MAND | XTOPT_MULTI},

According to the IPv4 SNAT/DNAT manpage, support for multiple ranges
was removed after 2.6.10. Has this changed?
If not, XTOPT_MULTI seems misplaced.

>+	case O_TO_SRC:
>+		if (cb->xflags & F_X_TO_SRC) {
>+			if (!kernel_version)
>+				get_kernel_version();
>+			if (kernel_version > LINUX_VERSION(2, 6, 10))
>+				xtables_error(PARAMETER_PROBLEM,
>+					   "SNAT: Multiple --to-source not supported");

It certainly is misplaced. IPv6 S/DNAT did not exist in any form in 2.6.10,
so we do not need to do the version check here.

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Patrick McHardy - Aug. 9, 2012, 9:31 p.m.
On Thu, 9 Aug 2012, Jan Engelhardt wrote:

>
> On Thursday 2012-08-09 22:11, kaber@trash.net wrote:
>> +
>> +static const struct xt_option_entry SNAT_opts[] = {
>> +	{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
>> +	 .flags = XTOPT_MAND | XTOPT_MULTI},
>
> According to the IPv4 SNAT/DNAT manpage, support for multiple ranges
> was removed after 2.6.10. Has this changed?
> If not, XTOPT_MULTI seems misplaced.
>
>> +	case O_TO_SRC:
>> +		if (cb->xflags & F_X_TO_SRC) {
>> +			if (!kernel_version)
>> +				get_kernel_version();
>> +			if (kernel_version > LINUX_VERSION(2, 6, 10))
>> +				xtables_error(PARAMETER_PROBLEM,
>> +					   "SNAT: Multiple --to-source not supported");
>
> It certainly is misplaced. IPv6 S/DNAT did not exist in any form in 2.6.10,
> so we do not need to do the version check here.

Right, I'm going to delete all this.
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Patch

diff --git a/extensions/libip6t_SNAT.c b/extensions/libip6t_SNAT.c
new file mode 100644
index 0000000..307be70
--- /dev/null
+++ b/extensions/libip6t_SNAT.c
@@ -0,0 +1,247 @@ 
+/*
+ * Copyright (c) 2011 Patrick McHardy <kaber@trash.net>
+ *
+ * Based on Rusty Russell's IPv4 SNAT target. Development of IPv6 NAT
+ * funded by Astaro.
+ */
+
+#include <stdio.h>
+#include <netdb.h>
+#include <string.h>
+#include <stdlib.h>
+#include <xtables.h>
+#include <iptables.h>
+#include <limits.h> /* INT_MAX in ip_tables.h */
+#include <linux/netfilter_ipv6/ip6_tables.h>
+#include <linux/netfilter/nf_nat.h>
+
+enum {
+	O_TO_SRC = 0,
+	O_RANDOM,
+	O_PERSISTENT,
+	O_X_TO_SRC,
+	F_TO_SRC   = 1 << O_TO_SRC,
+	F_RANDOM   = 1 << O_RANDOM,
+	F_X_TO_SRC = 1 << O_X_TO_SRC,
+};
+
+static void SNAT_help(void)
+{
+	printf(
+"SNAT target options:\n"
+" --to-source [<ipaddr>[-<ipaddr>]][:port[-port]]\n"
+"				Address to map source to.\n"
+"[--random] [--persistent]\n");
+}
+
+static const struct xt_option_entry SNAT_opts[] = {
+	{.name = "to-source", .id = O_TO_SRC, .type = XTTYPE_STRING,
+	 .flags = XTOPT_MAND | XTOPT_MULTI},
+	{.name = "random", .id = O_RANDOM, .type = XTTYPE_NONE},
+	{.name = "persistent", .id = O_PERSISTENT, .type = XTTYPE_NONE},
+	XTOPT_TABLEEND,
+};
+
+/* Ranges expected in network order. */
+static void
+parse_to(const char *orig_arg, int portok, struct nf_nat_range *range)
+{
+	char *arg, *start, *end = NULL, *colon = NULL, *dash, *error;
+	const struct in6_addr *ip;
+
+	arg = strdup(orig_arg);
+	if (arg == NULL)
+		xtables_error(RESOURCE_PROBLEM, "strdup");
+
+	start = strchr(arg, '[');
+	if (start == NULL)
+		start = arg;
+	else {
+		start++;
+		end = strchr(start, ']');
+		if (end == NULL)
+			xtables_error(PARAMETER_PROBLEM,
+				      "Invalid address format");
+
+		*end = '\0';
+		colon = strchr(end + 1, ':');
+	}
+
+	if (colon) {
+		int port;
+
+		if (!portok)
+			xtables_error(PARAMETER_PROBLEM,
+				   "Need TCP, UDP, SCTP or DCCP with port specification");
+
+		range->flags |= NF_NAT_RANGE_PROTO_SPECIFIED;
+
+		port = atoi(colon+1);
+		if (port <= 0 || port > 65535)
+			xtables_error(PARAMETER_PROBLEM,
+				   "Port `%s' not valid\n", colon+1);
+
+		error = strchr(colon+1, ':');
+		if (error)
+			xtables_error(PARAMETER_PROBLEM,
+				   "Invalid port:port syntax - use dash\n");
+
+		dash = strchr(colon, '-');
+		if (!dash) {
+			range->min_proto.tcp.port
+				= range->max_proto.tcp.port
+				= htons(port);
+		} else {
+			int maxport;
+
+			maxport = atoi(dash + 1);
+			if (maxport <= 0 || maxport > 65535)
+				xtables_error(PARAMETER_PROBLEM,
+					   "Port `%s' not valid\n", dash+1);
+			if (maxport < port)
+				/* People are stupid. */
+				xtables_error(PARAMETER_PROBLEM,
+					   "Port range `%s' funky\n", colon+1);
+			range->min_proto.tcp.port = htons(port);
+			range->max_proto.tcp.port = htons(maxport);
+		}
+		/* Starts with a colon? No IP info...*/
+		if (colon == arg) {
+			free(arg);
+			return;
+		}
+		*colon = '\0';
+	}
+
+	range->flags |= NF_NAT_RANGE_MAP_IPS;
+	dash = strchr(start, '-');
+	if (colon && dash && dash > colon)
+		dash = NULL;
+
+	if (dash)
+		*dash = '\0';
+
+	ip = xtables_numeric_to_ip6addr(start);
+	if (!ip)
+		xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
+			      start);
+	range->min_addr.in6 = *ip;
+	if (dash) {
+		ip = xtables_numeric_to_ip6addr(dash + 1);
+		if (!ip)
+			xtables_error(PARAMETER_PROBLEM, "Bad IP address \"%s\"\n",
+				      dash+1);
+		range->max_addr.in6 = *ip;
+	} else
+		range->max_addr = range->min_addr;
+
+	free(arg);
+	return;
+}
+
+static void SNAT_parse(struct xt_option_call *cb)
+{
+	const struct ip6t_entry *entry = cb->xt_entry;
+	struct nf_nat_range *range = cb->data;
+	int portok;
+
+	if (entry->ipv6.proto == IPPROTO_TCP ||
+	    entry->ipv6.proto == IPPROTO_UDP ||
+	    entry->ipv6.proto == IPPROTO_SCTP ||
+	    entry->ipv6.proto == IPPROTO_DCCP ||
+	    entry->ipv6.proto == IPPROTO_ICMP)
+		portok = 1;
+	else
+		portok = 0;
+
+	xtables_option_parse(cb);
+	switch (cb->entry->id) {
+	case O_TO_SRC:
+		if (cb->xflags & F_X_TO_SRC) {
+			if (!kernel_version)
+				get_kernel_version();
+			if (kernel_version > LINUX_VERSION(2, 6, 10))
+				xtables_error(PARAMETER_PROBLEM,
+					   "SNAT: Multiple --to-source not supported");
+		}
+		parse_to(cb->arg, portok, range);
+		break;
+	case O_PERSISTENT:
+		range->flags |= NF_NAT_RANGE_PERSISTENT;
+		break;
+	}
+}
+
+static void SNAT_fcheck(struct xt_fcheck_call *cb)
+{
+	static const unsigned int f = F_TO_SRC | F_RANDOM;
+	struct nf_nat_range *range = cb->data;
+
+	if ((cb->xflags & f) == f)
+		range->flags |= NF_NAT_RANGE_PROTO_RANDOM;
+}
+
+static void print_range(const struct nf_nat_range *range)
+{
+	if (range->flags & NF_NAT_RANGE_MAP_IPS) {
+		if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)
+			printf("[");
+		printf("%s", xtables_ip6addr_to_numeric(&range->min_addr.in6));
+		if (memcmp(&range->min_addr, &range->max_addr,
+			   sizeof(range->min_addr)))
+			printf("-%s", xtables_ip6addr_to_numeric(&range->max_addr.in6));
+		if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED)
+			printf("]");
+	}
+	if (range->flags & NF_NAT_RANGE_PROTO_SPECIFIED) {
+		printf(":");
+		printf("%hu", ntohs(range->min_proto.tcp.port));
+		if (range->max_proto.tcp.port != range->min_proto.tcp.port)
+			printf("-%hu", ntohs(range->max_proto.tcp.port));
+	}
+}
+
+static void SNAT_print(const void *ip, const struct xt_entry_target *target,
+                       int numeric)
+{
+	const struct nf_nat_range *range = (const void *)target->data;
+
+	printf(" to:");
+	print_range(range);
+	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
+		printf(" random");
+	if (range->flags & NF_NAT_RANGE_PERSISTENT)
+		printf(" persistent");
+}
+
+static void SNAT_save(const void *ip, const struct xt_entry_target *target)
+{
+	const struct nf_nat_range *range = (const void *)target->data;
+
+	printf(" --to-source ");
+	print_range(range);
+	if (range->flags & NF_NAT_RANGE_PROTO_RANDOM)
+		printf(" --random");
+	if (range->flags & NF_NAT_RANGE_PERSISTENT)
+		printf(" --persistent");
+}
+
+static struct xtables_target snat_tg_reg = {
+	.name		= "SNAT",
+	.version	= XTABLES_VERSION,
+	.family		= NFPROTO_IPV6,
+	.revision	= 1,
+	.size		= XT_ALIGN(sizeof(struct nf_nat_range)),
+	.userspacesize	= XT_ALIGN(sizeof(struct nf_nat_range)),
+	.help		= SNAT_help,
+	.x6_parse	= SNAT_parse,
+	.x6_fcheck	= SNAT_fcheck,
+	.print		= SNAT_print,
+	.save		= SNAT_save,
+	.x6_options	= SNAT_opts,
+};
+
+void _init(void)
+{
+	xtables_register_target(&snat_tg_reg);
+}